Mine roof bolt expanding shells



y 1965 F. P. DICKOW MINE ROOF BOLT EXPANDING SHELLS Filed May 14, 1963 INVENT OR. FREDERlCH P. DICHOW.

ATTORNEY United States Patent 3,181,414 MINE ROOF BGLT EXPANDING HELLS Frederick P. Dielrow, Auburn, Niifl, assigner to The Eastern Company, Naugatuck, Conn, a corporation of Connecticut Filed May 14, P363, Ser. No. 28%,232 4 Claims. (Cl. 85-75) This application is a continuation-in-part of applica tion Serial No. 813,243, filed May 4-, 1959 and now abandoned.

This invention relates to mine roof bolt expanding shells, and more particularly to a shell construction adapted to provide circumferential grip over a considerable length.

The practice of supporting mine roofs against cave-ins, as well as securing tunnel walls, and rock slides, by the application of long bolts extending relatively deep into the rock formation, and anchored therein by expanding shells, to form a natural bridge is relatively common. The bolts extend from the exposed surface, where the head and a plate Washer bear against the surface, into a hole drilled relatively deep into the rock formation, where the threaded end is fitted with an expanding shell. Such shells are generally located within a hard rock stratum, and expanded into solid gripping relation with the rock, through the action of a wedging member threaded on the bolt end. Many of such devices are capable of opposed diametral expansion only, whereas others tend to provide a non-uniform grip, lengthwise thereof. In some instances the devices provide insufficient initial grip on the bore surface to resist the thread ing torque necessary to start the expanding wedge.

The present invention is directed to an expanding shell, wherein provision is made for applying circumferential pressure substantially uniformly over a substantial length, and at the same time providing for ease in initial commencernent of the application of expanding pressure. The invention is further directed to an expanding shell having four active segments, arranged in joined pairs with provision for limited deformation of the interconnection of the individual segments of each pair to allow substantially uniform circumferential as well as lengthwise gripping action.

The invention is further directed to an expansion shell having expansion in four directions, and comprising two identical shell members, each of which is subdivided into two segments integrally joined at their lower ends, and in which one segment of each member is connected to the corresponding segment of the other member by a resilient yoke aflixed to the upper ends of the segments, the yoke being capable of resiliently spreading the lower ends of the segments. Still further the invention is directed to an expanding wedge and shell segments that have complemental wedge faces that are fiat transversely of the shell, and which are curved on a relatively long radius lengthwise of the shell, the wedge faces being slightly concave, lengthwise of the wedge and the segment faces being convex lengthwise of the segments, whereby the wedge may exert greater radial expanding effort as it moves further into the shell and closer to the juncture between the section segments at the lower end.

The above and other novel features of the invention will appear more fully hereinafter from the following detailed description when taken in conjunction with the accompanying drawings. It is expressly understood that the drawings are employed for purposes of illustration only and are not designed as a definition of the limits of the invention, reference being had for this purpose to the appended claims.

In the drawings, wherein like reference characters indicate like parts:

FZGURE l is a side elevational view of another ernbodiment of the expander;

FIGURE 2 is a top plan view of the expander of FIG URE 1;

FIGURE 3 is a side elevational view, with parts in quarter section, taken substantially on the line 33 of FIGURE 2;

FIGURE 4 is a side elevational view of the wedge member of FIGURE 1;

FIGURE 5 is a top plan view of the wedge member;

FIGURE 6 is a bottom plan view of the wedge memher; and

FIGURE 7 is a sectional view taken on the line 7-7 of FIGURE 5.

In the drawings, there is shown an expansion shell comprising two halves or sections 29 and 22, which are alike, and each section of which is divided in substantially similar segments 24 and 26 by a slot 28 extending from the upper end to a point short of the lower end to provide an integral portion 32 joining the two segments together. The segments have exterior arcuate saw tooth gripping teeth 42 effective to grip the wall of a bore in rock strata or the like into which the shell may be inserted, and individual teeth 46 to resist rotation.

The upper ends of the segments 26 of each section are provided on the exterior thereof with a dovetail shaped recess 34 into which the dovetailed ends 36 of the spring strap 38 are seated, the ends 36 being secured in place by swaging over the walls of the recesses 34, as at 40. The strap 38, may have a V bend in the bridge portion as at 42 to provide a reserve length of strap.

The inside faces 47 and 4-9 respectively of the segments 24 and 26 of each member are flat transversely of the segment and are curved lengthwise on a radius approximately six to seven times the length of the segments, the curved surface being convex lengthwise of each segment and providing a surface which flares up wardly and outwardly as indicated. The center of the radius of curvature is located substantially in the plane of the transverse end face 51 of the shell.

An expanding wedge 50 having four expanding wedge faces 52 are formed degrees from each other, and also formed so as to be complemental to the faces 47 and 49 of the segments 24 and 2d, of each of the shell members, the faces 52 being fiat transversely of the wedge and concave lengthwise on a curvature of a radius similar to that set forth for the segment faces 47 and 49. The wedge member has a threaded aperture 53 to receive a bolt 82, and opposed slots 58 and 6% to clear the legs of the strap 38, and opposed wings 62 and 64, adapted to slide within the slots 28 between the segments 24 and 26, the wings lying in a plane approximately 45 degrees from the plane of the slots 58 and 69.

In employing a shell of the type referred to, the lower edges 7i) of the segments 26, as for example viewed in FIGURE 3, are normally urged by the resiliency of the strap 33, to spread apart, in the manner and to the approximate extent indicated by the dotted lines 74), so that when the shell assembly is projected upwardly into a bore in the rock strata of a diameter to readily receive the shell assembly in its contracted size as shown in FIGURES 1 and 2, the lower edges 70 will be caused to bear yieldingly against the walls of the bore. When the shell assembly is located in the position in the bore, where it is to be expanded, the engagement of the edges 76 with the bore wall frictionally hold the shell members from rotating within the bore, and the edges 70 also dig into the bore wall to such an extent as to prevent the shell from falling out of the bore, by its own weight, or the weight of the shell and a bolt threaded in the wedge 54). Thus it is not essential that the operator hold the shell in place within the bore during the interval between placing the shell in position, and the subsequent expansion of the shell.

When the shell is placed within the bore, at its proper location, a plate or large washer 86 on the bolt 82 is in engagement with the mine roof. Thus upon rotation of the bolt 82., to draw the wedge 59 downwardly within the shell, the wedge is held against rotation, both by its flat faces 52, and the wings 62 and 64, which engage the flared surfaces 47 and 49 of the segments, and the slot between the segments 24 and 26 respectively, the shell resisting rotation by reason of the engagement of the edges 70 with the bore wall.

Once the bolt is turned enough to draw the wedge into the shell, there being tension on the bolt, all four segments of the shell are expanded outwardly and thus enhance the frictional grip upon the bore wall. Further tensioning of the bolt, and drawing the wedge further into the shell expands the shell and its four segments solidly against the bore wall to provide secure anchorage in four radial directions.

As the wedge moves downwardly within the shell, along the flared curved surfaces 47 and 49, the wedging angle gradually decreases, in order to facilitate the elfectiveness of the wedge in its expanding of the shell in four directions. The shell members may be formed of malleable iron castings or the like, and may be deformed by the radial wedge pressure, and as the wedge approaches the connection 32 between the segments of each member or section, greater expanding force may be required, because of the resistance of the bridge $2 to ready deformation. Thus the gradual change in the wedge angle of the wedging surfaces of the segments resulting from the flare or curvature 47 and 49, provides a gradual increase in mechanical advantage that can be exerted by the wedge for each increment of movement axially, as the wedge moves downwardly into the shell. The net effect is an increased radial pressure, which in turn provides an increase in holding power, so that the anchoring effect is made certain, with sufiicient expanding power to deform the connection 32, as may be necessary to obtain substantially uniform expansion in four radial directions.

It will be understood that each shell and its wedge form an assembly, and by applying a temporary sleeve around the lower ends of the assembly to hold the same contracted, prior to insertion in a rock strata bore, the wedge is confined to the shell, and if the wedge be provided with a bolt preparatory to insertion into a rock strata bore, the shell cannot become detached from the wedge, partlyby reason of the confining effect of the four segments, in surrounding the lower end of the wedge, and the presence of the legs of the strap 38 in the slots 58 and 68, as for example indicated in FIGURE 1. Immediately prior to insertion of the assembly with a bolt into a rock strata bore, such sleeve may be removed from the shell to permit it to expand at its lower end under the urge of the strap 38, and if the strap 38 has taken a set, the operator may spread the lower ends of the shell members to upset the strap, and restore sufficient resilience such that when the shell is inserted into the bore the lower edges 79 will engage the bore wall under suflicient yielding pressure.

in practice it may be desirable to provide initial expansion of the shell by wedge action by allowing the bolt end to engage the V'bend 4-2 of the strap 33, and thus create an initial hold of the shell against the bore wall, before applying further expansion force through rotation of the bolt and establishing tension thereby in the bolt, to draw the wedge into the shell. In such case the V bend provides for over travel of the bolt end, should the head end of the bolt, bearing against the mine roof result in upward movement during the compression of the rock strata between the expansion shell and bolt head.

Although a single embodiment of the invention has been illustrated and described, it is to be understood that the invention is not limited thereto. As various changes in the construction and arrangement may be made without departing from the spirit of the invention, as will be apparent to those skilled in the art, reference will be had to the appended claims for a definition of the limits of the invention.

What is claimed is:

l. A mine roof bolt expansion assembly comprising a shell composed of two separate semi-cylindrical malleable iron sections, each section having a slot extending centrally from the upper end to a point short of the lower end to provide a pair of segments and integral means connecting the segments of each section at the lower end, each segment having external gripping teeth and upwardly and outwardly flaring inside camming surfaces, said camming surfaces being straight crosswise of the segments, and convex lengthwise substantially the entire length of the segments, a U-shaped bridging resilient strap having depending substantially parallel side portions terminating with dovetail end portions aflixed in complemental dovetail recesses in the outside upper end of one segment of each of said sections, the side walls of said recesses being swaged over and rigidly engaging the dovetail end portions, and a wedge member axially disposed in the upper ends of said shell section and having an axially threaded bore, said wedge member having four wedge faces disposed at angles of degrees from one another and each face being straight transversely and concave lengthwise thereof and complemental to said camming' surfaces respectively at their upper ends, said wedge member having opposed side grooves loosely embracing the' side portions of said strap and opposed wings disposed in a plane 45 7 degrees from the plane of said grooves and adapted to slide in the slots between the segments of each section.

2. A mine roof bolt expansion'assembly comprising a shell composed of two separate semi-cylindrical malleable iron sections, each section having a slot extending centrally from the upper end to a point short of the lower end to provide a pair of segments and integral means connecting the segments of each section at the lower end, eachsegment having external gripping teeth and upwardly and outwardly flaring inside camming surfaces, said camming surfaces being straight crosswise of the segments, and convex lengthwise substantially the entire length of the segments, a U-shaped bridging resilient strap having depending substantially parallel side portions terminating with dovetail end portions aflixed in complemental dove- 0 tail recesses in the outside upper end of one segment of each of said sections, the side walls of said recesses being swaged over and rigidly engaging the dovetail end portions, and a'wedge member axially disposed in the upper ends of said shell section and having an axially threaded bore, said wedge member having four wedge faces disposed at angles of 90 degrees from one another and each face being straight transversely and concave lengthwise thereof and complemental to said camming surfaces respectively at their upper ends, said wedge member having opposed side grooves loosely embracing the side portions of said strap.

3. A mine roof bolt expansion assembly comprising a shell composed of two separate semi-cylindrical malleable iron sections, each section having a slot extending cen- 0 trally from the upper end to a point short of the lower end to provide a pair of segments and integral means connecting the segments of each section at the lower end, each segment having external gripping teeth and upwardly and outwardly flaring inside camming surfaces, said camming surfaces being straight crosswise of the segments, and convex lengthwise of the segments, a U-shaped bridging resilient strap havingdepending substantially parallel side portions terminating with dovetail end portions aflixed in complemental dovetail recesses in the outside upper end of one segment of each of said sections, the side walls of said recesses being swaged over and rigidly engaging the dovetail end portions, and a Wedge member axially disposed in the upper ends of said shell section and having an axially threaded bore, said Wedge member having four wedge faces disposed at angles of 90 degrees from one another and each face being straight transversely and concave lengthwise thereof and complemental to said camming surfaces respectively at their upper ends, said wedge member having opposed side grooves loosely em bracing the side portions of said strap and opposed wings disposed in a plane 45 degrees from the plane of said grooves and adapted to slide in the slots between the segments of each section, said upwardly and outwardly flaring camming surfaces of each of the segments comprising a cylindrical surface of a radius approximately 6 to 7 times the length or" the shell, and the center of which lies substantially in a plane transverse to the axis of the shell at the lower end of the shell.

4. A mine roof bolt expansion assembly comprising a shell composed of two separate semi-cylindrical malleable iron sections, each section having a slot extending centrally from the upper end to a point short of the lower end to provide a pair of segments and integral means connecting the segments of each section at the lower end, each segment having external gripping teeth and upwardly and outwardly flaring inside camrning surfaces, said carnming surfaces being straight crosswise of the segments, and convex lengthwise of the segments, a U-shaped bridging resilient strap having depending substantially parallel side portions terminating with dovetail end portions affixed in complemental dovetail recesses in the outside upper end of one segment of each of said sections, the side walls of said recesses being swaged over and rigidly engaging the dovetail end portions, and a Wedge member axially disposed in the upper ends of said shell section and having an axially threaded bore, said wedge member having four wedge faces disposed at angles of degrees from one another and each face being straight transversely and concave lengthwise thereof and complemental to said carnming surfaces respectively at their upper ends, said wedge member having on posed side grooves loosely embracing the side portions of said strap, said upwardly and outwardly flaring camming surfaces of each of the segments comprising a cylindrical surface of a radius approximately 6 to 7 times the length of the shell, and the center of which lies substantially in a plane transverse to the axis of the shell at the lower end of the shell.

References Cited by the Examiner UNITED STATES PATENTS 1,850,768 3/32 Peirce. 2,657,099 1/54 Lewis. 2,753,750 7/56 Dempsey. 2,8 87,062 5/59 McAfee. 3,000,25 4 9/ 61 Hottenstein.

FOREIGN PATENTS 5 82,602 4/ 34 Germany.

EDWARD C. ALLEN, Primary Examiner. 

1. A MINE ROOF BOLT EXPANSION ASSEMBLY COMPRISING A SHELL COMPOSED OF TWO SEPARATE SEMI-CYLINDRICAL MALLEABLE IRON SECTIONS, EACH SECTION HAVING A SLOT EXTENDING CENTRALLY FROM THE UPPER END TO A POINT SHORT OF THE LOWER END TO PROVIDE A PAIR OF SEGMENTS AND INTEGRAL MEANS CONNECTING THE SEGMENTS OF EACH SECTION AT THE LOWER END, EACH SEGMENT HAVING EXTERNAL GRIPPING TEETH AND UPWARDLY AND OUTWARDLY FLARING INSIDE CAMMING SURFACES, SAID CAMMING SURFACES BEING STRAIGHT CROSSWISE OF THE SEGMENTS, AND CONVEX LENGTHWISE SUBSTANTIALLY THE ENTIRE LENGTH OF THE SEGMENTS, A U-SHAPED BRIDGING RESILIENT STRAP HAVING A DEPENDING SUBSTANTIALLY PARALLEL SIDE PORTIONS TERMINATING WITH DOVETAIL END PORTIONS AFFIXED IN COMPLEMENTAL DOVETAIL RECESSES IN THE OUTSIDE UPPER END OF ONE SEGMENT OF EACH OF SAID SECTIONS, THE SIDE WALLS OF SAID RECESSES BEING SWAGED OVER AND RIGIDLY ENGAGING THE DOVETAIL END PORTIONS, AND A WEDGE MEMBER AXIALLY DISPOSED IN THE UPPER ENDS OF SAID SHELL SECTION AND HAVING AN AXIALLY THREADED BORE, SAID WEDGE MEMBER HAVING FOUR WEDGE FACES DISPOSED AT ANGLES OF 90 DEGREES FROM ONE ANOTHER AND EACH FACE BEING STRAIGHT TRANSVERSELY AND CONCAVE LENGTHWISE THEREOF AND COMPLEMENTAL TO SAID CAMMING SURFACES RESPECTIVELY AT THEIR UPPER ENDS, SAID WEDGE MEMBER HAVING OPPOSED SIDE GROOVES LOOSELY EMBRACING THE SIDE PORTIONS OF SAID STRAP AND OPPOSED WINGS DISPOSED IN A PLANE 45 DEGREES FROM THE PLANE OF SAID GROOVES AND ADAPTED TO SLIDE IN THE SLOTS BETWEEN THE SEGMENTS OF EACH SECTION. 